1. Field of the Invention
The present invention relates to a swash plate type compressor and, more particularly, to improved lubricating performance of the sliding contact surfaces of a swash plate and a shoe of the compressor.
2. Description of the Related Art
Hitherto, swash plate type compressors have been used as an apparatus for compressing refrigerant gas in automotive climate control systems. Such swash plate type compressors are equipped with a cylinder block assembly which has a plurality of cylinder bores provided parallel to a drive shaft; a swash plate secured to the drive shaft so as to be rotated by the drive shaft in the cylinder block assembly; pistons slidably fitted to reciprocate in the cylinder bores to compress the refrigerant gas; and shoes which are provided between the pistons and the swash plate which reciprocate the pistons in response to the rotation of the swash plate.
In the above swash plate type compressor, high load and high sliding speed regularly act on the sliding contact surfaces of the swash plate and the shoes. Accordingly the sliding contact surfaces of the swash plate and the shoes are apt to become dry due to any insufficient supply of lubricating oil. This poses a problem especially where aluminum or an aluminum alloy is used as the base metal of the swash plate because of its light weight.
To solve this problem, as disclosed in Japanese Patent Application Laid-open No. 60-22080, at least the swash plate or the shoes employ aluminum or an aluminum alloy as the base metal with the sliding contact surface thereof coated with an alloy which contains molybdenum disulfide (MoS2) as the main component. Another solution has been proposed in Japanese Patent Application Laid-open No. 2-130272, in which the surface of the swash plate is plated with an alloy, in which tin is the main component, to form a surface treating layer.
In the former solution, although the solid lubricant layer, containing molybdenum disulfide as the main component, exhibits good lubricating performance, it has such shortcomings as poor wear resistance and a short service life.
The latter solution provides a high degree of hardness and accordingly good wear resistance; however, it is disadvantageous in that the lubricating performance is not as high as that of the former solution.